Fig. 6. Simulated (curves) and measured (points) changes in alkalinity with detention time in Howe Bridge, Morrison, and Buck Mountain anoxic limestone drains (ALDs) including exponential decay and the rate constants, k' and k'', derived from cubitainer tests. Dashed curves were computed for the first-order rate model (Eq. [7]) and solid curves for the second-order rate model (Eq. [10]). Measured data are typical values along the profile as shown in Fig. 2.